U.S. patent application number 16/486716 was filed with the patent office on 2020-01-16 for coil device.
This patent application is currently assigned to IHI CORPORATION. The applicant listed for this patent is IHI CORPORATION. Invention is credited to Motonao NIIZUMA, Kenji NISHIMURA.
Application Number | 20200020478 16/486716 |
Document ID | / |
Family ID | 64737598 |
Filed Date | 2020-01-16 |
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United States Patent
Application |
20200020478 |
Kind Code |
A1 |
NISHIMURA; Kenji ; et
al. |
January 16, 2020 |
COIL DEVICE
Abstract
A coil device includes a coil unit for stowing a coil part, and
a heat dissipation unit thermally connected to the coil unit. The
heat dissipation unit has a heat dissipation body, a heat
dissipation fin movable relative to the heat dissipation body, and
a fin drive mechanism for driving the heat dissipation fin. The
heat dissipation unit has a heat dissipation configuration in which
the heat dissipation fin projects from the heat dissipation body in
a direction intersecting a winding axis, and a stowed configuration
in which the heat dissipation fin is stowed in the heat dissipation
body.
Inventors: |
NISHIMURA; Kenji; (Koto-ku,
Tokyo, JP) ; NIIZUMA; Motonao; (Koto-ku, Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IHI CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
IHI CORPORATION
Tokyo
JP
|
Family ID: |
64737598 |
Appl. No.: |
16/486716 |
Filed: |
June 21, 2018 |
PCT Filed: |
June 21, 2018 |
PCT NO: |
PCT/JP2018/023620 |
371 Date: |
August 16, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01F 38/14 20130101;
H01F 27/22 20130101; B60L 53/302 20190201; B60M 7/00 20130101; H01F
27/2876 20130101; B60L 53/12 20190201; H01F 27/025 20130101; H02J
50/12 20160201; H02J 50/10 20160201 |
International
Class: |
H01F 27/28 20060101
H01F027/28; H01F 38/14 20060101 H01F038/14; H02J 50/10 20060101
H02J050/10; B60L 53/12 20060101 B60L053/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2017 |
JP |
2017-122068 |
Claims
1. A coil device, comprising: a coil unit for stowing a coil part
and having a main surface; and a heat dissipation unit thermally
connected to the coil unit, wherein the heat dissipation unit
includes: a heat dissipation body thermally connected to the main
surface; a heat dissipation member movable relative to the heat
dissipation body and thermally connected to the heat dissipation
body; and a drive part for driving the heat dissipation member, and
wherein the heat dissipation unit has a first configuration in
which the heat dissipation member projects from the heat
dissipation body in a direction along the main surface, and a
second configuration in which the heat dissipation member is stowed
in the heat dissipation body.
2. The coil device according to claim 1, wherein when the coil part
is being supplied with an electric current, the heat dissipation
unit is in the first configuration.
3. The coil device according to claim 2, wherein when the heat
dissipation unit is in the first configuration, a length of the
heat dissipation member projecting from the heat dissipation body
is a predetermined desired projection length.
4. The coil device according to claim 2, wherein the coil device
supplies power to a paired coil device or receives power from the
paired coil device, and when the heat dissipation unit is in the
first configuration, the length of the heat dissipation member
projecting from the heat dissipation body is determined based on an
amount of misalignment between the coil part of the coil device and
the coil part of the paired coil device.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a coil device.
BACKGROUND ART
[0002] Patent Literatures 1 and 2 disclose techniques that focus on
heat generated by a coil in a wireless power transfer device. The
wireless power transfer device of Patent Literature 1 has a liquid
type cooling mechanism. Specifically, the wireless power transfer
device of Patent Literature 1 includes a flow path through which a
fluid circulates. The heat generated by the coil is absorbed by a
liquid that flows through the flow path. The wireless power
transfer device of Patent Literature 2 thermally protects
electronic components by utilizing a partition wall that has
thermal insulation properties. The wireless power transfer device
of Patent Literature 2 externally releases joule heat that is
generated by a power transmission coil utilizing a member which has
a high thermal conductivity.
CITATION LIST
Patent Literature
[0003] Patent Literature 1: Japanese Unexamined Patent Publication
No. 2012-228123
[0004] Patent Literature 2: Japanese Unexamined Patent Publication
No. 2016-103645
SUMMARY OF INVENTION
Technical Problem
[0005] In the field relating to wireless power transfer devices, it
is desired that the heat generated by a coil during conduction is
efficiently released. The wireless power transfer device of Patent
Literature 1 efficiently releases the heat generated by the coil by
the liquid type cooling mechanism. However, the liquid type cooling
mechanism requires a flow path to be formed inside the coil device.
Moreover, the liquid type cooling mechanism requires accessory
devices such as a pump for circulating the liquid. Thus, this may
prevent downsizing of the wireless power transfer device.
[0006] The present disclosure describes a coil device which enables
both efficient heat dissipation and downsizing.
Solution to Problem
[0007] One embodiment of the present disclosure is a coil device.
The coil device includes a coil unit for stowing a coil part and
having a main surface, and a heat dissipation unit thermally
connected to the coil unit. The heat dissipation unit includes a
heat dissipation body thermally connected to the main surface, a
heat dissipation member movable relative to the heat dissipation
body and thermally connected to the heat dissipation body, and a
drive part for driving the heat dissipation member. The heat
dissipation unit has a first configuration in which the heat
dissipation member projects from the heat dissipation body in a
direction along the main surface, and a second configuration in
which the heat dissipation member is stowed in the heat dissipation
body.
Effects of Invention
[0008] The coil device according to the present disclosure enables
both efficient heat dissipation and downsizing.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is an exploded perspective view showing a coil
device.
[0010] FIG. 2 is a plan view of a heat dissipation unit of the coil
device.
[0011] FIG. 3(a) is a perspective view showing a stowed
configuration and FIG. 3(b) is a perspective view showing a heat
dissipation configuration.
[0012] FIG. 4 is a diagram showing a configuration of a wireless
power transfer system having coil devices.
[0013] FIG. 5 is a diagram showing a misalignment between the coil
devices.
[0014] FIG. 6 is a diagram showing a variation of the coil
device.
[0015] FIG. 7(a) is a diagram showing the coil device of FIG. 6 in
use, and FIG. 7(b) is a diagram showing the coil device of FIG. 6
in an alternative use.
[0016] FIG. 8(a) is a diagram showing the stowed configuration of
another variation of the coil device, and FIG. 8(b) is a diagram
showing the heat dissipation configuration of the other variation
of the coil device.
[0017] FIG. 9(a) is a plan view of the coil device shown in FIG.
8(a), and FIG. 9(b) is a plan view of the coil device shown in FIG.
8(b).
[0018] FIG. 10(a) is a diagram showing a heat dissipation sheet
folded, and FIG. 10(b) is a diagram showing the heat dissipation
sheet unfolded.
[0019] FIG. 11(a) is a diagram showing the stowed configuration of
yet another variation of the coil device, and FIG. 11(b) is a
diagram showing the heat dissipation configuration of the yet
another variation of the coil device.
[0020] FIG. 12(a) is a diagram showing the stowed configuration of
yet another variation of the coil device, and FIG. 12(b) is a
diagram showing the heat dissipation configuration of the yet
another variation of the coil device.
[0021] FIG. 13(a) is a diagram showing the stowed configuration of
yet another variation of the coil device, and FIG. 13(b) is a
diagram showing the heat dissipation configuration of the yet
another variation of the coil device.
DESCRIPTION OF EMBODIMENTS
[0022] One embodiment of the present disclosure is a coil device.
The coil device includes a coil unit for stowing a coil part and
having a main surface, and a heat dissipation unit thermally
connected to the coil unit. The heat dissipation unit includes a
heat dissipation body thermally connected to the main surface, a
heat dissipation member movable relative to the heat dissipation
body and thermally connected to the heat dissipation body, and a
drive part for driving the heat dissipation member. The heat
dissipation unit has a first configuration in which the heat
dissipation member projects from the heat dissipation body in a
direction along the main surface, and a second configuration in
which the heat dissipation member is stowed in the heat dissipation
body.
[0023] In the coil device, the heat dissipation body of the heat
dissipation unit is thermally connected to the coil unit. The heat
dissipation member is thermally connected to the heat dissipation
body. Heat generated by the coil part that is housed in the coil
unit is thus transferred to the heat dissipation member via the
heat dissipation body. The heat dissipation member projects from
the heat dissipation body in a direction along the main surface of
the coil unit. A heat dissipation area that contributes to heat
dissipation is thus increased. As a result, the amount of heat
dissipated by heat radiation and heat transfer to the air is
increased. The coil device is thus capable of efficiently
dissipating heat. The heat dissipation member is stowed in the heat
dissipation body. The coil device can thus be downsized. That is,
since the coil device has the heat dissipation member that can be
inserted into and removed from the heat dissipation body, the coil
device enables both efficient heat dissipation and downsizing.
[0024] When the coil part is being supplied with an electric
current, the heat dissipation unit may be in the first
configuration. When the coil part is being supplied with an
electric current, the coil part generates heat. When the coil part
is generating heat, the heat dissipation unit is in the first
configuration in which the heat dissipation member is projected.
The increased heat dissipation area thus enables the heat generated
by the coil part to be efficiently dissipated. As a result, the
influence of the heat on the coil unit is reduced so that the coil
device can be stably operated.
[0025] When the heat dissipation unit is in the first
configuration, a length of the heat dissipation member projecting
from the heat dissipation body may be a predetermined desired
projection length. This configuration enables to achieve a heat
dissipation configuration that corresponds to the mode of heat
generation.
[0026] The coil device supplies power to a paired coil device or
receives power from the paired coil device, and when the heat
dissipation unit is in the first configuration, the length of the
heat dissipation member projecting from the heat dissipation body
may be determined based on an amount of misalignment between the
coil part of the coil device and the coil part of the paired coil
device. When the coil device and the paired coil device are
misaligned, the coil parts are misaligned. The misalignment between
the coil parts causes flux leakage. The flux leakage causes the
coil parts to generate heat corresponding to the amount of
misalignment. The length of the heat dissipation member projecting
from the heat dissipation body is determined on the basis of the
misalignment between the coil parts. The projection length of the
heat dissipation member can thus be a length corresponding to the
rise in temperature. As a result, the power required to drive the
coil device can be reduced.
[0027] The coil device according to the present disclosure is
described in detail below with reference to the accompanying
drawings. Like elements are given like reference signs in the
description of the drawings and redundant explanation is omitted.
Additionally, an orthogonal coordinate system shown in the diagrams
may be used for the description of the drawings. In the description
below, "front" corresponds to a positive X direction. "Back"
corresponds to a negative X direction. "Left" corresponds to a
positive Y direction. "Right" corresponds to a negative Y
direction. "Up" corresponds to a positive Z direction. "Down"
corresponds to a negative Z direction.
[0028] The coil device is used in a wireless power transfer system.
As shown in FIG. 1, a coil device 1 includes a coil unit 2 and a
heat dissipation unit 3.
[0029] The coil unit 2 is a rectangular parallelepiped having a
rectangular shape in plan view. The coil unit 2 has a power
transmission surface 2a and a base connection surface 2b (main
surface). The power transmission surface 2a faces another coil
device 1. The base connection surface 2b is fixed to the heat
dissipation unit 3. In the coil device 1, the heat dissipation unit
3 and the coil unit 2 are stacked in this order along a vertically
upward direction (Z axis direction). In other words, the coil unit
2 is placed on top of the heat dissipation unit 3. The coil unit 2
includes a housing 4, a coil 6 (coil part), a coil holding plate 7,
and a ferrite plate 8.
[0030] The housing 4 has substantially the same shape as the heat
dissipation unit 3 in plan view. The housing 4 forms a space that
houses the coil 6, the coil holding plate 7, and the ferrite plate
8. The housing 4 has a case body 9 and a lid 11.
[0031] The coil 6 is formed by a conductive wire that is wound in a
substantially rectangular spiral within the same plane. The coil 6
generates an induced current. The coil 6 is a so-called circular
coil. A circular coil is a type of coil in which a conductive wire
is wound in a flat spiral around a winding axis S. A flat spiral is
the shape of the conductive wire wound around the winding axis S
from the outside to the inside or from the inside to the outside so
as to surround the same. It is only required that the coil 6 has a
configuration in which the conductive wire is wound in a flat
spiral. The coil 6 thus may be a single-layer coil or a multi-layer
coil. Additionally, there may be a plurality of the winding axes S
and spirals within the same plane. The coil 6 viewed from a
direction of the winding axis S may be of various shapes, such as
rectangular, circular, or oval. A litz wire in which a plurality of
conductor strands insulated from each other are twisted together
may, for example, be used as the conductive wire. The conductive
wire may be a copper or aluminum solid wire, a bus bar, or the
like. It should be noted that the coil may be a solenoid coil.
[0032] The coil holding plate 7 is a planar member for holding the
coil 6. The coil holding plate 7 is a so-called bobbin. The coil
holding plate 7 has, for example, grooves into which the coil 6 is
fit. A material having electrical insulating properties (e.g.,
silicone or polyphenylene sulfide resin) is used as the material
for the coil holding plate 7. The grooves into which the coil 6 is
fit may be formed on the lid 11. Additionally, the coil 6 may be
hardened by an adhesive material and/or varnish. In this case, the
coil holding plate 7 may be omitted.
[0033] The ferrite plate 8 is, for example, a rectangular planar
ferrite core. The ferrite plate 8 is magnetic and controls the
direction of magnetic lines of force generated by the coil 6. The
ferrite plate 8 also converges the magnetic lines of force. The
ferrite 8 may have a shape and size, for example, that are
substantially equal to the shape and size of the coil holding plate
7 in plan view. The shape and size of the ferrite plate 8 are not
limited to a square. The ferrite plate 8 may be set to any shape
and size that can be stowed in the housing 4.
[0034] The heat dissipation unit 3 is thermally connected to the
coil unit 2 on a lower side of the coil unit 2. The heat
dissipation unit 3 is disposed so as to contact a road surface or
the like. The heat dissipation unit 3 is nonmagnetic and is
electrically conductive. The heat dissipation unit 3 is formed from
a material that has high rigidity (e.g., aluminum or copper). The
heat dissipation unit 3 ensures the rigidity of the coil device 1
as a whole. The heat dissipation unit 3 blocks external outflow of
the flux leakage. The heat dissipation unit 3 dissipates the heat
generated in the coil unit 2. In other words, the heat dissipation
unit 3 functions as a so-called heat sink.
[0035] As shown in FIGS. 1 and 2, the heat dissipation unit 3
includes a heat dissipation body 12, a pair of heat dissipation
fins 13 (heat dissipation members), and a fin drive mechanism 14
(drive part). The heat dissipation body 12 includes a housing
connection surface 12a (first mounting surface), a road surface
connection surface 12b (second mounting surface), and fin side
surfaces 12c. The heat dissipation body 12 has a fin housing part
15 (see FIG. 2). The housing connection surface 12a is the top
surface when disposed on a road surface. The housing connection
surface 12a faces the base connection surface 2b of the coil unit
2. The road surface connection surface 12b is the bottom surface
when disposed on the road surface. The road surface connection
surface 12b faces the road surface. The fin side surfaces 12c
connect the housing connection surface 12a to the road surface
connection surface 12b. The fin housing part 15 is a recess formed
in the road surface connection surface 12b. The fin housing part 15
has fin openings 15a formed on the fin side surfaces 12c. The shape
of the fin openings 15a conforms to the external shape of the heat
dissipation fins 13.
[0036] The heat dissipation fins 13 are movable relative to the
heat dissipation body 12. The heat dissipation fins 13 each
includes a heat dissipation surface 13a and a movable surface 13b.
The heat dissipation surface 13a has a plurality of protrusions D.
Each of the plurality of protrusions D extend in a Y-axis
direction. The plurality of protrusions D are separated from each
other in an X-axis direction. Such shape increases the surface area
of the heat dissipation surface 13a. Heat is dissipated efficiently
as a result. The heat dissipation surface 13a is formed slidable
relative to the heat dissipation body 12. The heat dissipation
surface 13a is in constant contact with the fin housing part 15 of
the heat dissipation body 12. This contact includes direct contact
between the heat dissipation surface 13a and the fin housing part
15, and indirect contact between the heat dissipation surface 13a
and the fin housing part 15 with a member such as grease
therebetween. For example, a small gap is formed between the heat
dissipation surface 13a and the fin housing part 15. For example, a
thermally conductive silicone and/or oil that do not naturally
volatilize may be disposed in this gap. A thermally conductive
silicone sheet having abrasion resistance may be inserted in the
gap. Such configuration enables the heat dissipation fins 13 to be
inserted into and removed from the heat dissipation body 12
smoothly and the heat to be conducted efficiently from the heat
dissipation body 12 to the heat dissipation fins 13.
[0037] The movable surface 13b is formed on a lower side of the
heat dissipation surface 13a. The movable surface 13b faces the
road surface. The movable surface 13b is not fixed to the road
surface. The movable surface 13b is thus movable relative to the
road surface. For example, the movable surface 13b is formed
slightly above the road surface connection surface 12b of the heat
dissipation body 12. That is, a gap may be formed between the
movable surface 13b and a road surface G (see FIG. 4).
[0038] The fin drive mechanism 14 reciprocates the pair of heat
dissipation fins 13 in the Y-axis direction. The fin drive
mechanism 14 includes a worm gear 17 and an electric motor 18. The
worm gear 17 is a component having helical teeth on a rod that
extends in the Y-axis direction. One end of the worm gear 17 is
screwed into one of the heat dissipation fins 13. The other end of
the worm gear 17 is screwed into the other heat dissipation fin 13.
The electric motor 18 has a gear 18a that meshes with the teeth of
the worm gear 17. The electric motor 18 applies torque to the worm
gear 17 through the gear 18a. The electric motor 18 is capable of
forward and reverse rotations. The electric motor 18 rotates the
worm gear 17 a predetermined number of turns. By setting the number
of turns of the worm gear 17 to a predetermined number, the
projection lengths of the heat dissipation fins 13 can be
controlled to a desired length. A desired projection length is, for
example, a length required for the temperature of a predetermined
portion of a power transmission coil device 24 to be lower than a
threshold. A desired projection length is also, for example, a
length required to limit the rise in temperature of a predetermined
portion of the power transmission coil device 24. By setting the
projection length to a minimally required length to lower the
temperature below the threshold and/or to limit the rise in
temperature, energy consumption of the electric motor 18 can be
reduced. It can also reduce the possibility of a vehicle V riding
over the heat dissipation fins 13.
[0039] The fin drive mechanism 14 shown in FIG. 1 drives the pair
of the heat dissipation fins 13 by the one worm gear 17. This
configuration causes the projection lengths of the pair of the heat
dissipation fins 13 to be always the same. However, the length of
one of the heat dissipation fins 13 may be different from the
projection length of the other heat dissipation fin 13. For
example, one of the heat dissipation fins 13 may be stowed in the
heat dissipation body 12 with only the other heat dissipation fin
13 being projected. To do so, the fin drive mechanism 14 is
provided for each of the one of the heat dissipation fins 13 and
the other heat dissipation fin 13. It is only required that there
is a fin drive mechanism to drive one of the heat dissipation fins
13 and a fin drive mechanism to drive the other heat dissipation
fin 13.
[0040] As shown in FIGS. 3(a) and 3(b), the heat dissipation unit 3
has two or more different configurations. FIG. 3(a) shows a
configuration in which the heat dissipation fins 13 are stowed in
the heat dissipation body 12 (stowed configuration, second
configuration). FIG. 3(b) shows a configuration in which the heat
dissipation fins 13 project from the heat dissipation body 12 (heat
dissipation configuration, first configuration).
[0041] In the coil device 1, the heat dissipation body 12 of the
heat dissipation unit 3 is thermally connected to the coil unit 2.
The heat dissipation body 12 is thermally connected to the heat
dissipation fins 13. The heat generated by the coil 6 that is
housed in the coil unit 2 is thus transferred to the heat
dissipation fins 13 via the heat dissipation body 12. The heat
dissipation fins 13 project from the heat dissipation body 12 in a
direction (Y-axis direction) intersecting the winding axis S (see
FIG. 1). The heat dissipation area that contributes to heat
dissipation is thus increased. Heat is dissipated efficiently as a
result. In addition, the heat dissipation fins 13 are stowed in the
heat dissipation body 12. The coil device 1 can thus be downsized.
Consequently, due to the heat dissipation fins 13 that can be
inserted into and removed from the heat dissipation body 12, the
coil device 1 enables both efficient heat dissipation and
downsizing.
[0042] An operation set to the stowed configuration and an
operation set to the heat dissipation configuration may correspond
to a power feeding operation to another coil device 1. For example,
when no power is fed, no electric current is supplied to the coil
6. Since the coil 6 does not generate heat, it is not necessary to
actively dissipate heat. The heat dissipation fins 13 are thus
stowed in the heat dissipation body 12 (stowed configuration). The
stowed configuration enables the coil device 1 to be downsized. On
the other hand, when power is fed, an electric current is supplied
to the coil 6. Since the coil 6 generates heat, the heat is
actively dissipated. The heat dissipation fins 13 are thus caused
to project from the heat dissipation body 12 (heat dissipation
configuration). The heat dissipation configuration enlarges the
heat dissipation area that contributes to heat dissipation. Heat
dissipation efficiency is improved as a result.
[0043] A wireless power transfer system including the coil device 1
according to the embodiment will now be explained. As shown in FIG.
4, a wireless power transfer system 21 charges a battery 29 that is
mounted on the vehicle V, such as an electric vehicle or a hybrid
vehicle. The wireless power transfer system 21 supplies power
directly to a drive source, such as an electric motor. The vehicle
V includes components necessary for travel such as an electric
motor, a steering wheel, and brakes. However, these components are
omitted in FIG. 4.
[0044] The wireless power transfer system 21 includes a power
transmitter 22 installed on the road surface G and a power receiver
23 mounted on the vehicle V. The power transmitter 22 and the power
receiver 23 each has the coil device 1 according to the embodiment.
Hereinafter, the coil device 1 of the power transmitter 22 is
referred to as the power transmission coil device 24, and the coil
device 1 of the power receiver 23 as the power reception coil
device 26 (paired coil device). When the power transmission coil
device 24 and the power reception coil device 26 are in close
proximity, the coil 6 (see FIG. 1) of the power transmission coil
device 24 and the coil 6 of the power reception coil device 26
(paired coil part) are in close proximity to one another. In this
proximal state, an electromagnetic coupling circuit is formed by
the pair of the coils 6. The electromagnetic coupling circuit
wirelessly transfers power from the coil 6 on a power transmitting
side to the coil 6 on a power receiving side by electromagnetic
coupling of the coils 6. The electromagnetic coupling circuit may
be an electromagnetic induction coupling circuit or a magnetic
resonance coupling circuit.
[0045] The power transmission coil device 24 and the power
reception coil device 26 face each other in an up-down direction
and are spaced apart by a predetermined distance. The power
transmission coil device 24 protrudes upward from the road surface
G. The power reception coil device 26 is attached, for example, to
a lower surface of a chassis B of the vehicle V.
[0046] The power receiver 23 includes the power reception coil
device 26 (coil device), a power reception circuit 27, and a
charging circuit 28. The power reception coil device 26 receives
power (AC power) wirelessly supplied from the power transmission
coil device 24 of the power transmitting side. The power reception
circuit 27 converts the AC power from the power reception coil
device 26 into DC power. The power reception circuit 27 then
outputs the DC power to the charging circuit 28. The charging
circuit 28 converts the power (DC power) from the power reception
circuit 27 into a desired power. The charging circuit 28 supplies
the desired power to the battery 29. The battery 29 is a
rechargeable battery mounted on the vehicle V. The battery 29 is,
for example, a secondary battery such as a lithium ion battery or a
nickel hydrogen battery. The battery 29 supplies power to a travel
motor and the like not shown.
[0047] The power transmitter 22 includes the power transmission
coil device 24 (coil device), a power transmission circuit 31, a
rectifier circuit 32, and a control device 34.
[0048] The power transmission coil device 24 is installed on the
road surface G.
[0049] The power transmission circuit 31 converts the power
supplied from the rectifier circuit 32 into AC power (high
frequency power). The power transmission circuit 31 provides the AC
power to the power transmission coil device 24.
[0050] The rectifier circuit 32 rectifies the AC power supplied
from an external power source 33. In other words, the rectifier
circuit 32 converts the AC power into DC power. The rectifier
circuit 32 may be omitted when the external power source 33 is a DC
power source.
[0051] The external power source 33 supplies power required to
generate power to be transmitted to the vehicle V.
[0052] The control device 34, which is an electronic control unit
includes, for example, a central processing unit (CPU), a read only
memory (ROM), and a random access memory (RAM). The control device
34 controls the circuits (the rectifier circuit 32, the power
transmission circuit 31, and the like) of the power transmitter
22.
[0053] The control device 34 controls a heat dissipation operation
of the power transmission coil device 24. Specifically, the control
device 34 provides a control signal to the electric motor 18 (see
FIG. 1). The control signal relates to the projection lengths of
the heat dissipation fins 13. The projection lengths of the heat
dissipation fins 13 relate to the number of rotations of the
electric motor 18. The control device 34 thus rotates the electric
motor 18 the number of times that corresponds to the projection
lengths.
[0054] The control device 34 controls the heat dissipation fins 13
such that the heat dissipation fins 13 are in the stowed
configuration (see FIG. 3(a)) when no electric current is supplied
to the power transmission coil device 24. When in the stowed
configuration, outer end surfaces 13c of the heat dissipation fins
13 may be flush with the fin side surfaces 12c. It should be noted
that the outer end surfaces 13c may be arranged inward of the fin
side surfaces 12c. The outer end surfaces 13c may protrude slightly
from the fin side surfaces 12c.
[0055] The control device 34 controls the heat dissipation fins 13
such that the heat dissipation fins 13 are in the heat dissipation
configuration (see FIG. 3(b)) when an electric current is supplied
to the power transmission coil device 24. The heat dissipation
configuration refers to the configuration in which the heat
dissipation fins 13 project predetermined lengths from the fin side
surfaces 12c. The predetermined lengths may be the lengths of the
heat dissipation fins 13 when the heat dissipation fins 13 are
mechanistically in the most projected positions. The predetermined
lengths may be determined using various variables relating to the
wireless power transfer system 21. For example, the predetermined
lengths may be determined on the basis of the amount of
misalignment between the power transmission coil device 24 and the
power reception coil device 26. They may also be determined on the
basis of the amount of misalignment between the coil 6 of the power
transmission coil device 24 and the coil 6 of the power reception
coil device 26.
[0056] Misalignment may be described by transmission efficiency
between the power transmission coil device 24 and the power
reception coil device 26. For example, when there is no
misalignment, it can be described that they are in a positional
relationship that achieves the maximum transmission efficiency. No
misalignment may also be described as a state in which the center
of a surface in a front-back direction (X-axis direction) of one of
the coils 6 is coincident in the up-down direction (Z-axis
direction) with the center of a surface in the front-back direction
of the other coil 6. No misalignment may also be described as a
positional relationship defined as there being no misalignment, for
example, in a specification or a user manual of a wireless power
transfer system in which the power transmission coil device 24 is
used. Misalignment may be defined as the difference between the
actual positions and these reference positions that indicate that
there is no misalignment.
[0057] Assume as shown in FIG. 5 that the power reception coil
device 26 is misaligned with the power transmission coil device 24
in a horizontal direction (Y-axis direction). In this
configuration, assume that the heat dissipation fins 13 are
composed of a soft magnetic material (e.g., soft ferrite). When
viewed from a vertical direction (Z-axis direction), there are
regions R1, R2 where the power transmission coil device 24 does not
overlap with the power reception coil device 26. These regions R1,
R2 may cause flux leakage between the power transmission coil
device 24 and the power reception coil device 26. When flux leakage
occurs, a desired transmission efficiency may not be obtained. The
control device 34 thus controls projection lengths L1, L2 of the
heat dissipation fins 13 to eliminate the non-overlapping regions
R1, R2. The projection lengths L1, L2 are the lengths from the fin
side surfaces 12c of the heat dissipation body 12 to the outer end
surfaces 13c of the heat dissipation fins 13. The control device 34
causes the projection length L1 of the other heat dissipation fin
13 to be longer than the projection length L2 of the one heat
dissipation fin 13. Such configuration enables flux leakage to be
reduced. Decrease in the transmission efficiency is prevented as a
result.
[0058] When the power transmission coil device 24 also has a heat
dissipation unit, similar control may be implemented. Flux leakage
can be further reduced in this case. Decrease in the transmission
efficiency is further prevented as a result.
[0059] A switching operation between the stowed configuration and
the heat dissipation configuration of the heat dissipation fins 13
need not be strictly synchronous with an electric current supply
operation to the coil 6. Synchronous, here, means that when supply
of the electric current to the coil 6 starts, an operation of
causing the heat dissipation fins 13 to project starts at the same
time, and the heat dissipation configuration is maintained while
the supply of the electric current to the coil 6 continues, and
when the supply of the electric current to the coil 6 stops,
transition from the heat dissipation configuration to the stowed
configuration starts at the same time, and the stowed configuration
is maintained while the supply of the electric current to the coil
6 is stopped. Employing control to immediately transition from the
heat dissipation configuration to the stowed configuration when the
supply of the electric current to the coil 6 stops, prevents a
charged vehicle V from riding over the heat dissipation fins 13
when the vehicle V moves from its position above the power
transmission coil device 24.
[0060] It is only required that the power transmission coil device
24 is in the heat dissipation configuration at least while the
supply of the electric current to the coil 6 continues. Thus, when
the supply of the electric current to the coil 6 stops, transition
from the heat dissipation configuration to the stowed configuration
need not take place immediately. For example, the transition from
the heat dissipation configuration to the stowed configuration may
take place when a predetermined time has passed after the supply of
the electric current to the coil 6 is stopped. The timing of the
transition may be, for example, when the temperature at a
predetermined location of the power transmission coil device 24
falls below a threshold. Such control enables the heat dissipation
fins 13 to remain projected when a charged vehicle V moves and
another vehicle V moves into place above the power transmission
coil device 24 immediately thereafter. The heat dissipation
operation can thus be continued. Power for driving the heat
dissipation fins 13 can also be reduced. Furthermore, the time for
moving the heat dissipation fins 13 in and out is eliminated. Use
efficiency of the wireless power transfer system 21 can be improved
as a result.
[0061] The coil device of the present disclosure has been described
in detail above based on the embodiment thereof. However, the coil
device of the present disclosure is not limited to the embodiment
above. Many variations of the coil device of the present disclosure
are possible without departing from the spirit of the
disclosure.
[0062] Heat dissipation members are not limited to a metal material
and need only be of a material having good thermal conductivity. A
material further having flexibility and shape memory
characteristics in addition to good thermal conductivity may also
be used as the material for forming the heat dissipation members.
Such material includes shape memory alloy, silicone, and the like.
As shown in FIG. 6, a coil device 1A includes a coil unit 2, and a
heat dissipation unit 3A. The heat dissipation unit 3A has heat
dissipation fins 13A (heat dissipation members). The heat
dissipation fins 13A have protrusions DA that extend in parallel
relative to fin side surfaces 12c. The plurality of the protrusions
DA are formed spaced apart from each other in a drive direction
(Y-axis direction). The heat dissipation fins 13A employing such
material deform when run over by a tire T, as shown in FIG. 7(a),
so that the effect on a vehicle V to which the tire T belongs can
be reduced. The vehicle V is thus not damaged. As shown in FIG.
7(b), the heat dissipation fins 13A recover a predetermined shape
after a predetermined period of time has passed.
[0063] The heat dissipation members are not limited to those having
a predetermined shape as long as they have a predetermined
rigidity. For example, as shown in FIGS. 8(a) and 8(b), a coil
device 1B includes a coil unit 2 and a heat dissipation unit 3B.
The heat dissipation unit 3B has heat dissipation sheets 37 (heat
dissipation members). The heat dissipation sheets 37 may be formed
from a flexible material such as a sheet member. The heat
dissipation sheets 37 formed from such material have a folded shape
for being stowed (stowed configuration, see FIG. 8(a)), and a
spread-out shape for dissipating heat (heat dissipation
configuration, see FIG. 8(b)).
[0064] The heat dissipation unit 3B shown in FIGS. 9(a) and 9(b)
includes the heat dissipation sheets 37, supports 38, guide bars
39, racks 41, and electric motors 42. The supports 38 are attached
to distal edges of the heat dissipation sheets 37. Distal ends of
the guide bars 39 are fixed to corresponding one ends of the
supports 38. The guide bars 39 are slidably supported at base ends
thereof by guide rails 43 formed on a heat dissipation body 12A.
Distal ends of the racks 41 are fixed to the corresponding other
ends the supports 38. The racks 41 engage with pinion gears 44 of
the electric motors 42 that are attached to the heat dissipation
body 12A. In such configuration, rotating the electric motors 42
causes the pinion gears 44 to rotate. When the pinion gears 44
rotate, the racks 41 move linearly. When the racks 41 move, the
support bars 38 attached to the racks 41 move. The heat dissipation
sheets 37 can thus be deployed and stowed. Such configuration
enables the heat dissipation sheets 37 to be stowed compactly (see
FIG. 9(a)). A space P for mounting various components can thus be
provided in the heat dissipation body 12A.
[0065] The folding configuration of the heat dissipation sheets is
also not limited. Other than the folding configuration of the
dissipation sheets in an accordion-like fashion as shown in FIGS. 8
and 9, a folding configuration which is referred to as the Miura
fold may be employed, such as heat dissipation sheets 37A shown in
FIG. 10(a) (stowed state) and FIG. 10(b) (heat dissipation
state).
[0066] The direction in which the heat dissipation members project
is not limited to one axial direction. For example, as shown in
FIGS. 11(a) and 11(b), a coil device 1C includes a coil unit 2 and
a heat dissipation unit 3C. In addition to a pair of first heat
dissipation fins 46 which are capable of being projected in a
direction of a first axis A1 (Y-axis direction), the heat
dissipation unit 3C may also have second heat dissipation fins 47
which are capable of being projected in a direction of a second
axis A2 (X-axis direction). The second axis A2 is perpendicular to
the first axis A1. Such configuration enlarges the heat dissipation
area, so that the heat dissipation efficiency is further
improved.
[0067] The heat dissipation body 12 is not limited to a rectangular
shape in plan view. For example, as shown in FIGS. 12(a) and 12(b),
a coil device 1D includes a coil unit 2D and a heat dissipation
unit 3D. A heat dissipation body 12D of the heat dissipation unit
3D may have a round shape in plan view. Such configuration also
enables the coil device 1D to have first heat dissipation fins 48
and second heat dissipation fins 49 that project in different
directions.
[0068] The operation of moving the heat dissipation members in and
out of the heat dissipation body is not limited to the operation of
linearly moving the heat dissipation members as in the coil device
1 of the first embodiment. For example, as shown in FIGS. 13(a) and
13(b), a coil device 1E includes a coil unit 2E and a heat
dissipation unit 3E. The heat dissipation members of the heat
dissipation unit 3E are tabular heat dissipation plates 51. The
heat dissipation plates 51 rotate about drive axes S1 and fan out.
The heat dissipation unit 3E of the coil device 1E has a plurality
of the heat dissipation plates 51. The corners of the heat
dissipation plates 51 are provided with drive shaft mechanisms (not
shown). The drive shaft mechanisms drive each of the heat
dissipation plates 51 to a different rotation position.
[0069] The embodiments above describe the coil device of the
present disclosure applied to a wireless power transfer system. The
coil device of the present disclosure is not limited to being
applied to a wireless power transfer system. The coil device of the
present disclosure can also be applied to a coil device that is
used in an environment in which there is no paired coil device. For
example, the coil device of the present disclosure may by applied
to an inductive heating system and/or an eddy current flaw
detection system.
INDUSTRIAL APPLICABILITY
[0070] The coil device of the present disclosure enables both
efficient heat dissipation and downsizing.
REFERENCE SIGNS LIST
[0071] 1, 1A, 1B, 1C, 1D, 1E Coil device [0072] 2, 2D, 2E Coil unit
[0073] 2a Power transmission surface [0074] 2b Base connection
surface (main surface) [0075] 3, 3A, 3B, 3C, 3D, 3E Heat
dissipation unit [0076] 4 Housing (coil unit) [0077] 6 Coil (coil
part) [0078] 7 Coil holding plate [0079] 8 Ferrite plate [0080] 9
Case body [0081] 11 Lid [0082] 12, 12A Heat dissipation body [0083]
12a Housing connection surface [0084] 12b Road surface connection
surface [0085] 12c Fin side surface [0086] 13, 13A Heat dissipation
fin (heat dissipation member) [0087] 13a Heat dissipation surface
[0088] 13b Movable surface [0089] 13c Outer end surface [0090] 14
Fin drive mechanism (drive part) [0091] 15 Fin housing part [0092]
15a Fin opening [0093] 17 Worm gear [0094] 18 Electric motor [0095]
21 Wireless power transfer system [0096] 22 Power transmitter
[0097] 23 Power receiver [0098] 24 Power transmission coil device
[0099] 26 Power reception coil device (paired coil device) [0100]
27 Power reception circuit [0101] 28 Charging circuit [0102] 29
Battery [0103] 31 Power transmission circuit [0104] 32 Rectifier
circuit [0105] 33 External power source [0106] 34 Control device
[0107] 37, 37A Heat dissipation sheet (heat dissipation member)
[0108] 38 Support [0109] 39 Guide bar [0110] 41 Rack [0111] 42
Electric motor [0112] 43 Guide rail [0113] 44 Pinion gear [0114]
46, 48 First heat dissipation fin [0115] 47, 49 Second heat
dissipation fin [0116] 51 Heat dissipation plate [0117] A1 First
axis [0118] A2 Second axis [0119] B Chassis [0120] D, DA Protrusion
[0121] G Road surface [0122] L1, L2 Projection length [0123] R1, R2
Region [0124] S Winding axis [0125] S1 Drive axis [0126] T Tire
[0127] V Vehicle
* * * * *